Variable switch operated positioning system



March 23, 1954 D. BENNETT VARIABLE SWITCH OPERATED POSITIONING SYSTEM 2 Sheets-Sheet 1 Filed Feb. 26, 1955 LOAD FIG.

INVENTOR. MAURICE D. BENNETT AGENT a March 23, 1954 M. D. BENNETT 2,673,313

. 2 Sheets-Sheet 2 FlGURE 4 95 92 9s FIGURE 5 i-u 94 9s 9? f INVENTOR.

MAURICE D. BENNETT BY i Em; fl f AGENT Patented Mar. 23, 1954 VARIABLE SWITCH OPERATED POSITIONING SYSTEM Maurice D. Bennett, Glenbrook, Conn., assignor to The Reflectone Corporation,

Stamford,

Conn., a corporation of Connecticut Application February 26, 1953, Serial No. 338,994

This invention relates to a means for transmitting information from one place to another and has particular reference to a ystem in which mechanical motion is transmitted electrically to be reproduced at a remote location. The present application is an alternateidesign of the mechanism disclosed in my copending application for Letters Patent, Serial Number 327,141, filed December 20, 1952, now Patent No. 2,668,263, issued February 2, 1954.

Prior devices which transmit mechanical information to a remote point are either mechanical or electrical. The flexible shaft is a wholly mechanical device for transmitting such information but its application and use is limited by the practical length of the flexible cable. In the electrical field the generic namesynchroap plies to various types of electro-magnetic devices which when used in the combination of a transmitter and a receiver transmit mechanical rotation electrically to a remote point.

These synchros are rather complex and are therefore expensive positioning devices which require accurate phasing of voltages and other care during manufacturing and later use in the field. The present device being an electro-mechanical system is characterized bygreat simplicity thereby being applicable where the, use of synchros is not economically feasible.

One of the objects of this invention is to provide a positioning system which avoids one or more of the disadvantages of prior art arrangements. M v v v I Another object of this invention is to provide an electro-mechanical positioning system in which mechanical displacement is sensed and transmitted electrically to a remote point for reproduction as mechanical motion. I V

, Another object of the invention is the use of a positioning system using revolving cams, the relative positions of which are reproduced at a remote point.

Still another object of the inventionisithe provision of a remote positioning system characterized by extreme simplicity and greatly re- :duced cost. v 1

The invention comprises a pair of variable switching means. Each switching means is equipped with a first and a second revolving cam which rotate in the same direction and at the same speed, The second cam bymeans of adifferential is angularly adjustable withresp'ectto '7 Claims. (01. 318-13) The consecutive opening and closing of these circuits is actuated by the cyclic rotation of said first and said second cam respectively of the switching means associated therewith. A motor adapted for bi-directional rotation is connected tosaid switches which cause said motor to stand still when the actuating arms of said switches occupy. the same relative position. Means are provided for positioningthe adjustable cam of one of said switching means in accordance with the rotation of said motor when the switches are caused to occupy differing relative positions.

For a better understanding of the present invention together with other and further objects thereof reference is made to the following description taken in connection with the accompanying drawings in which:

Figure l is a top view of the variable switching means;

Figure 2 is a cross sectional view of the switching means taken along the line 2-2 of Figure 1;

Figure 3 is a cross sectional view taken along the line 33 of Figure 1;

Figure 4 is a schematic view of the positioning system employing a pair of variable switching means; and

Figure 5 is a schematic wiring diagram of a motor useable for the positioning system.

Explaining first the operation of the variable switching means, the basic element of the present positioning system, reference is made to Figures 1, 2 and 3 in which a base Ill supports two vertical bearing plates II and 12 which carry nearly all of the rotating members. A constant speed motor I3 is mounted on the base and turns a gear H! which in turn drives a gear l5, loose on shaft [6 but secured to a first bevel gear I! which is part of a differential gear mechanism. Gear l5 also meshes with another gear [8 which carries a cam 20 and rotates freely on shaft 2|.

A cam follower roller 22 is resiliently pressed against the edge of cam 20 and is coupled to a switch mechanism 23, commonly termed a microswitch. This switch is constructed with a toggle action and its characteristics are such that operating arm 24 must be moved a definite distance to one side of a central position to operate the switch arm in one direction, and a similar definite distance to the other sideot the central position to operate the switch in the other direction. This means that when the switch arm 22 is held in the central position the switch contacts may be either open or closed, depending upon the previous arm movement.

The cam face of cam 20 is a circle except for one depression and the switch mechanism 23 is adjusted so that this cam face holds the arm 24 in the central position. When, during an operation, the roller 22 drops into depression 26 the switch is opened if it had previously been closed and after being opened the switch is held in that condition until operated upon by some other force which will move the arm 24 in a direction away from cam face .20.

Shaft I6 is journalled in plates H and I2 and supports gears l5, l1 near one plate and a pair of similar gears 26, 21 near the other plate. These gears rotate freely on shaft I6. A bevel gear 26 meshes with bevel gears 26 and I1 and turns on a stub shaft 30 which is part of block 3| secured to shaft l6. Shaft l6 also is secured to a manually operable dial 32 which may extend beyond the base and which is engaged by a friction pad 33.

Gear 21, which is secured to bevel gear 26,

A second cam 31 is secured to bar 36 and has a cam face which engages roller 22 to move arm 24 and close the contacts in switch 23. After the contacts have been closed, the return of arm 24 to its central position does not open the contacts until the roller moves into depression 25.

The operation of this device is as follows: With the motor l3 running at or near constant speed, gears l6 and 36 revolve in the same direction and at the same speed and carry cams 20 and 31 around their common axis in an unchanged relative position. If the cams are in the positions shown in Figure 3 and if they are turning in the direction indicated, the switch contacts will be made when roller 22 is engaged by cam 31 and then opened by depression 25, thereby being in a closed position for a short fraction of the time cycle represented by the complete revolution of gears l6 and 36.

m order to increase the time interval during which the contacts are closed, dial 32 is turned manually in counterclockwise direction, turning shaft 30 and bevel gear 28. This momentarily increases the speed of gears 26 and 21 and advances gears 34, 35 and 36 together with cam 31 to set a new angular position between depression '25 and the end of cam 31. The new arrangement supplies the load with an electrical power pulse of longer duration than previously and results in a longer duty cycle for the controlled load.

The time interval may be shortened by turning dial 32 in a clockwise direction; reversing the above described operation.

Toggle switches are generally supplied with two stationary contact points and arranged so that one circuit is made when a second circuit is opened. This type of switch may be used with a reversing motor which can be connected to run in one direction when one set of contacts is closed and to run in the opposite direction when the second set of contacts is closed. Such an arrangement comprises an integration system, the final result being controlled by the relative setting of the two cams.

It is not necessary to connect the constant speed motor I3 to a driving gear H as shown in Figure l. The motor may be coupled to shaft 2|, in which case gear It must be secured to the shaft and gear 36 must be free to rotate on it as described above. The device may be made with a cage type differential instead of the bevel type and any type of toggle switch can be used with the device as long as its characteristics include a central position where the switch may be open or closed, depending upon its previous actuation.

Having now described in detail the operation of the variable switching means, reference is made to Figure 4 which shows schematically the positioning system making use of a pair of variable switching means. A driving motor 40 running at or near constant speed, drives via gears 4|, 42 and 43 a first variable switching means which includes the two revolving cams 44 and 45 described in Figures 1, 2 and 3. Cam 45 is angularly adjustable with respect to the depression 46 of cam 44 by means of dial 41 secured to gear 46 and acting upon gear 49. Dial 41 in Figure 4 occupies the same position and performs the same function as dial 32 in Figure 1. A toggle switch 50 adapted to open alternately one circuit when a second circuit is closed, is operated by earns 44 and 45 by virtue of its operating arm 5| contacting these cams.

In a similar manner as described above, a second motor 58 drives via gears 59 and 60, a second variable switching means which includes cam. 6| and adjustable cam 62. A second toggle switch 63 is actuated by rotation of cams 6| and 62.

A reversible or bidirectional motor has a rotor 64 and is equipped with two selectively energizable field windings 65a and 65b. The coils are adapted to establish opposing flux patterns so that the selective energizing of either coil determines the rotation of the rotor 64. Field winding 65a. is connected to switches 50 and 63 via a source of electrical energy 66, conductors 10, 1|, 12 and 13. In a similar manner field winding 65b is connected to the single pole double throw switches 50 and 63 via a source of electrical energy 14, conductors 15, 16, 11 and 13. It will be seen that if the switches 56 and 63 are in the pression) the currentfiow to coil 65a is interrupted while coil 65b remains energized thereby obtaining rotational motion of rotor 64 and shaft 81. Shaft 81 by virtue of pinion 18 fastened thereon, meshing rack 13, rack and gear 6| transmits its motion to adjustable cam 62 in such a manner as to causeadjustable cam 62 to occupy the same relative position with respect to cain6l as adjustablecam 45 with respect to cam 44. Thus, a follow-up system or positioning system is achieved because as long as both switching mechanisms are in the same relative position, both field coils are 'energ'ized thereby holding-therotor 64 ina locked position. If"however the switching mechanisms do not occupy the same relative position with respect to one another, only onefieldcoil is energized which results in a motion of'the rotor. This resultant motion is applied upon gear 8| to cause adjustable cam 62 to occupy the same relative position with respect to cam 61 as cam 45 with respect to cam 44. As soonas this condition is reached, both field coils become energized again and rotor 64 is retained still. It will be obvious that the motor must be of such type as to be equipped with a high internal impedance'in order to have a relatively low locked rotor current. The usual type of synchronous clock motor or the'hysteresis synchronous motor are typical types of motors which fulfill this requirement. 1

In Figure 5 an alternate example is shown which employs a series type direct current motor or a direct current motor with the field being a permanent magnet. The motor 99 is connected to a pair of double pole single throw switches 9| and 92 respectively by means of conductors 93, 94, 95 and 96. The switches are interconnected by conductors 91 and98. A source of electrical energy 99 is connected via a current limiting resistor I90 to conductors 97 and 98.

When the contacts of both switches are open motor 96 is deenergized thereby causing no rotation of the. rotor. Closing switch 92 when switch 9| is open will cause the motor to operate in one direction, while energizing switch-9 i when switch 92 is open will reverse the current flow to'cause the motor to turn in the opposite direction. When the contacts of both switches are closed the motor is by-passed andthe current I fiow is limited only by the limiting resistor W9.

is greater than is permissible by the limited length of rack 19 or rack 89. When using such an arrangement adjustable cam 45 for instance may be rotated continuously through any angle without being limited by linear motion on the receiving end of the system.

While there have been described and illustrated specific embodiments of the invention, it will be obvious that various changes and modifications may be made therein without departing from the field of the invention which should be limited only by the scope of the appended claims. Other features of the invention disclosed are claimed in my co-pending application for Letters Patent, Serial Number 316,741, with filing date of October 24, 1952.

What is claimed is:

l. A positioning system comprising a pair of variable switching means, each of said switching means equipped with a first and a second revolv ing cam rotating in the same direction and at the same speed and said second cam by means of a differential being angularly adjustable with re-- spect to said first cam, a switch adapted to alternately open one circuit when a second circuit is closed associated with each of said switching means, the consecutive opening and closing of said circuits actuated by the cyclic rotation of said first and said second cam respectively of the switching means associated therewith, a

motor adapted for bidirectional rotation-connected to said switches with circuit means which cause said motor to stand still when the. actuating arms of said switches occupy thesame rela+ tive position and to rotate when the actuating arms occupy differing .relative positions, and means for positioning the adjustable cam of .one of said switching means inaccordance with the rotation of said motor when theswitches are caused to occupy differing relative positions.

2. A positioning system comprising a primary and a secondary rotating variable switching means driven at substantially the same speed, each of said switching means equipped with a first and a second revolving cam rotating in the same direction and at the samespeed and said second cam by means of a differential being angularly adjustable with respect to saidfirst earn, a switch adapted to alternately open one. circuit when a second circuit is closed associated with each of said switching means, theconsecutive opening and closing of saidlcircuits actuatedby the cyclic rotation of said first and said. second cam respectively of the switching means. associated therewith, a motor adapted for bidirectional rotation connected to said switches and to a source of voltage, said switches interconnected with one another to cause said motor :to stand still when the actuating armsiof. said switches occupy the same relative position and to cause rotation of said motor when the actuatingarins of said switches occupy diifering relative :positions and means to transmitmotion of said motor caused by differing relative switchpositionsto the adjustable cam of said .secondaryswitching means to causesaid cam. to assume the. same "angular displacement with respect to itsfirst cam as the angular displacement selected between: th cams of said primary switching means. .1 A:

3. A positioning system comprising a pair of variable switching means, eachof said switching means equipped'with a first and a second revolving cam rotating in the same direction and at the same speed and said second: cam by means of a differential being angularly adjustable with respect to said first earn, a switch adapted to alternately open one circuit whena second cir- =cuit. .is closed, associated with each oi said switching .means, the. consecutiveopening closing of said circuits actuated by the cyclic rotation of said first and said second cam respectively of the switching means associated therewith, a bidirectionally operable motor having a plurality of field windings adapted to be selectively energized to determine the rotational direction of said motor, said field windings connected to said switches to cause zero rotation of said motor when the actuating mechanisms of said switches occupy the same relative position and means for positioning the adjustable cam of one of said switching means in accordance with the rotation of said motor when motion is imparted upon said motor by difiering relative positions of said switches.

, 4. A positioning system comprising a primary and a secondary variable switching means, each of said switching means equipped with a first and second revolving cam rotating in the same direction and at the same speed and said second cam by means of a differential being angularly adjustable with respect to said first cam, a toggle switch adapted to alternately open one circuit when a second circuit is closed associated with each of said switching means, the consecutive opening and closing of said circuits actuated by 7 the cyclic rotation of said first andsaid second cam respectively of the switching means associated therewith, a bidirectionally operable motor having a plurality of field windings adapted to be selectively energized to determine the rotational direction of said motor, said field windings connected via a source of electrical energy to said switches, interconnection between said switches to cause zero rotation of said motor when the actuating mechanisms of both switches occupy the same relative position and to cause rotation of said motor when the switches do not occupy the same position, transmission means between the shaft of said motor and the adjustable cam of said secondary switching means to cause this adjustable cam to become angularly displaced when rotation is imparted uponthe motor caused by a difference in the position of said switches.

5. A positioning system comprising a pair or variable switching means, each of switching means equipped with a first and a second revolving cam rotating in the same direction and at the same speed and said second cam by means of a difierential being an ularly adjustable with respect to said first cam, a toggle switch associated with each of said switching means, toggle switches cyclically actuated by the rotations or the first and second cam of the associated switching means, a motor adapted for bidirectional rotation connected to said switches with circuit means which cause said motor to stand still when the contacts of said switches occupy the same relative positions and to rotate when the switch contacts occupy differing relative positions, and means for positioning the adjustable cam of one of said switching means responsive to the rotation of said motor when the switches are caused to occupy differing relative positions.

6. A positioning system comprising a pair of variable switching means, each of said switching means equipped with a first and a second revolving cam rotating in the same direction and at the same speed and said second cam by means of a differential being angularly adjustable with respect to said first cam, a double pole toggle switch associated with each of said switching means, said toggle switches cyclically actuated -by the rotations of the first and second cam of the switching means associated therewith, amotor adapted for bidirectional rotation connected to said switches with circuit means which cause said motor to stand still when the contacts of said switches occupy the same relative positions and to rotate when the switch contacts occupy differing relative positions, means to limit the current through the motor when it is standing still, and means for positioning the adjustable cam of one of said switching means responsive to the rotation of said motor when the switches are caused to occupy difiering relative positions.

7. A positioning system comprising a pair of variable switching means, each of said switching means equipped with a first and a second revolving cam rotating in the same direction and at the same speed and said second cam by means of a differential being angularly adjustable with respect to said first cam, a double pole toggle switch associated with each of said switching means, said toggle switches cyclically actuated by the rotations of the first and second cam of the switching means associated therewith, a motor adapted for bidirectional rotation connected to said switches, said switches interconnected to cause said motor to rotate in one direction when one switch is closed and to rotate in the opposite direction when the other switch is closed and to stand still when the contacts of both switches occupy the same relative positions, a source of electrical energy connected to said switches, means in series with said source of electrical energy to cause the current through said motor to be limited when both switches are closed, and means for positioning the-adjustable cam ofone of said switching means responsive to the rotation of said motor when the contacts of said switches are caused to occupy differing relative positions.

MAURICE D. BENNETT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,476,106 Mejean July 12, 1949 2,557,741 Hoffman et a1 June 19, 1951 2,604,527 Buehler July 22, 1952 

